Although they used to have more differences (like the Detail tool didn't used to be able to pick up annotation, which it can optionally do now), one subtle difference is that the detail window will be at twice the scale of the original, whereas the worksheet keeps the same scale. Also, the Worksheet has a one-click ability to capture the entire plan or drawing, unlike the Detail tool.
Richard
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Richard Morrison, Architect-Interior Designer
AC26 (since AC6.0), Win10